The present invention relates to a photographic printing apparatus and an image forming method by which a desired image is printing exposed onto a silver halide color photographic photosensitive material, and specifically relates to a technology by which an exposing mask is effectively formed and a high quality image is reproduced onto a sheet of printing paper.
Conventionally, when normal photographic images (landscape, people, or the like), color illustration images (logotypes or trade marks of companies, or the like), and character images (characters on greeting cards, or the like) exist simultaneously and are printed onto silver halide color photographic photosensitive material (hereinafter, called printing paper), the following operations are carried out. An exposing mask on which color illustration images and character images simultaneously exist, is made; the exposing mask is arranged on an exposing mask holder provided on a printing section in which color illustration images and character image are printed, (hereinafter, called subsidiary exposing section) in a printer; a frame of an ordinary negative film is set on a negative film holder disposed on a photographic image printing section (hereinafter, called primary exposing section); and primary exposing and subsidiary exposing operations are carried out individually on the printing paper so that a photographic print, on which photographic images, color illustration images and character images simultaneously exist, can be obtained.
The exposing mask is made for printing a large number of original images. Generally, in production processes of exposing masks (a light transmission type negative film) for printing color illustration images, a silver halide photosensitive film, which is exposed by lighting from the rear of the exposing mask in order to expose a printing paper in the printing process, is used. In these production processes of the exposing mask, initially, an original designed image is separated into three colors by a scanner, and three sheets of monochrome masks corresponding to the respective color images are made without processing the three color data. Next, a color image is formed on the same silver halide photosensitive film by three exposures, using these monochrome masks and light sources which are separated into colors of B, G and R. The silver halide photosensitive film, which was thus exposed, is developed, and then the exposing mask, by which the color images are printed, is made.
Further, there is a method in which an image is formed by exposing a printing paper three times, that is, R, G and B exposure, using a CRT (Cathode Ray Tube). However, in this method, it takes about 10 seconds due to the limitation of the quantity of light of the CRT to print a sheet of paper. Accordingly, this method is inappropriate for printing a large number of sheets of paper. A printing method, in which the exposing mask is made for printing using a light source, is more appropriate for printing a large number of sheets of paper because it takes only about 0.2 sec. for an exposing operation.
Complicated processes are necessary for making the exposing mask, and accordingly, it is fairly difficult to make the exposing mask using a simple process.
Accordingly, the exposing mask is limited to those designs previously made by processing stations, and accordingly, customer's detailed requests can not be fully satisfied, which is a problem.
Further, when color balance on the mask is unsatisfactory, it takes a long period of time to appropriately set exposing time and filter conditions in a photographic printing apparatus, which is another problem.